As a trace gas detector for a gas chromatograph, detectors adopting various methods, such as a TCD (Thermal Conductive Detector) and an ECD (Electric Capture Detector), are being proposed and put to practical use, and a detector that is currently most generally used is an FID (Flame Ionization Detector). The FID achieves a wide dynamic range (about six figures) by ionizing sample gas by a hydrogen flame and measuring the ionization current thereof. However, there is a disadvantage that it is not suitable for detection of inorganic gas and fire-retardant gas. On the other hand, there is a discharge ionization current detector which performs detection by generating an excited species of inert gas, such as He, N2, Ar, Ne or Xe, by plasma that is generated by high-voltage discharge and by ionizing a sample. A PDD (Pulsed Discharge Detector), which is one of such discharge ionization current detectors, generates plasma by causing spark discharge by application of a pulsed high voltage. A method that uses plasma does not need hydrogen and, generally, the ionization efficiency of a sample is increased compared to the FID and the sensitivity is high, having sensitivity for inorganic gas and fire-retardant gas, but there is a disadvantage that the dynamic range is narrow compared to the FID.
Also, in contrast to the PDD, there is a discharge ionization current detector which adopts a method for generating plasma by dielectric-barrier discharge (Patent Document 1). With the dielectric-barrier discharge, since the surface of a discharge electrode is covered with a dielectric material, there is not much emission of thermal electrons, secondary electrons and the like that occur in the case of generating discharge between metal electrodes, and the stability of plasma generation is high. Also, a discharge current is suppressed by the dielectric material, and thus, there are characteristics that deterioration of electrodes and heat generation at electrodes may be suppressed, and that the durability is high.